1. Cross Reference to Related Applications
This application is related to co-pending, commonly assigned, U.S. patent application Ser. No. 10/914,634 entitled “Server Verification of Secure Electronic Messages,” filed Aug. 10, 2004, the disclosure of which is incorporated herein by reference in its entirety.
2. Field of the Invention
The present invention relates generally to an electronic messaging system that is capable of processing encoded messages and information. In particular, the disclosure is directed to a system in which an electronic message server performs some functions typically performed by a mobile wireless communications device having secure electronic messaging capability. In order to perform such functions, the server is capable of storing and maintaining, for example, certificates, associated with the mobile wireless communications devices that use the server. Accordingly, the present disclosure is directed to systems and methods for ensuring that the information, such as certificates, associated with the devices that use the server and which are stored on the server is kept up to date.
3. Related Art
Exchanging cryptographically encoded secure electronic messages and data, such as, for example, e-mail messages, is well known. In many known electronic message exchange schemes, signatures, encryption or both are commonly used to ensure the integrity and confidentiality of information being exchanged between a sender and a recipient of the electronic messages. In an e-mail system, for example, the sender of an e-mail message may either sign the message, encrypt the message or both sign and encrypt the message. These actions may be performed using well-known standards, such as, for example, Secure Multipurpose Internet Mail Extensions (S/MIME), Pretty Good Privacy™ (PGP™), OpenPGP, and numerous other secure e-mail standards.
In general, secure e-mail messages are relatively large. For example, S/MIME can increase the size of an e-mail message by a factor of ten or more in some situations. This size augmentation, caused for example by appending certificates to the message, presents difficulties, especially in devices that have a limit on the size of a message that can be processed, such as, for example, a mobile wireless communications device. Such a device may also experience difficulty handling a message wherein only a portion of the message has been transferred to the device because of the above-mentioned size limitations.
To the extent processor intensive actions, such as, for example, verification of signatures, can be performed by a more powerful and faster device, such as, for example, a server, advantages with respect to device efficiency, speed and improved user satisfaction can be realized by a reduction of computational overhead of the device. However, in order to take advantage of the improved processor capability and speed of the server, it is necessary for the server to have the proper information available to perform the functions otherwise performed by the mobile device. For example, if the server maintains a list of certificates associated with devices using the server, the server will have the ability to verify signatures for the user. This is an especially powerful tool if the message is long. In addition, the server can effectively compress the certificate information that is sent in the S/MIME message. For example, if the server knows that a device already has a particular certificate on it, then when an S/MIME message to the device includes that certificate, the server can safely remove this certificate. This saves a great deal of bandwidth for each certificate that is removed. The bandwidth savings realized by removing redundant certificate information is especially useful because the certificate information limits the amount of bandwidth available for the message. However, to realize the efficiencies attendant with having device certificate information resident at the server, it is important to keep this certificate information up to date. To that end, what is needed is a system and method for synchronizing information, such as, for example, certificates, between the server and its associated devices.